#snow-overlay {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 9999;
  overflow: hidden;
}

.snowflake {
  position: absolute;
  top: -10px;
  color: white;
  user-select: none;
  animation-name: snow-fall;
  animation-timing-function: linear;
  animation-iteration-count: infinite;
}

@keyframes snow-fall {
  from { transform: translateY(-10vh); }
  to   { transform: translateY(110vh); }
}